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esp4.c
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// SPDX-License-Identifier: GPL-2.0-only
#define pr_fmt(fmt) "IPsec: " fmt
#include <crypto/aead.h>
#include <crypto/authenc.h>
#include <linux/err.h>
#include <linux/module.h>
#include <net/ip.h>
#include <net/xfrm.h>
#include <net/esp.h>
#include <linux/scatterlist.h>
#include <linux/kernel.h>
#include <linux/pfkeyv2.h>
#include <linux/rtnetlink.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/in6.h>
#include <net/icmp.h>
#include <net/protocol.h>
#include <net/udp.h>
#include <net/tcp.h>
#include <net/espintcp.h>
#include <linux/highmem.h>
struct esp_skb_cb {
struct xfrm_skb_cb xfrm;
void *tmp;
};
struct esp_output_extra {
__be32 seqhi;
u32 esphoff;
};
#define ESP_SKB_CB(__skb) ((struct esp_skb_cb *)&((__skb)->cb[0]))
/*
* Allocate an AEAD request structure with extra space for SG and IV.
*
* For alignment considerations the IV is placed at the front, followed
* by the request and finally the SG list.
*
* TODO: Use spare space in skb for this where possible.
*/
static void *esp_alloc_tmp(struct crypto_aead *aead, int nfrags, int extralen)
{
unsigned int len;
len = extralen;
len += crypto_aead_ivsize(aead);
if (len) {
len += crypto_aead_alignmask(aead) &
~(crypto_tfm_ctx_alignment() - 1);
len = ALIGN(len, crypto_tfm_ctx_alignment());
}
len += sizeof(struct aead_request) + crypto_aead_reqsize(aead);
len = ALIGN(len, __alignof__(struct scatterlist));
len += sizeof(struct scatterlist) * nfrags;
return kmalloc(len, GFP_ATOMIC);
}
static inline void *esp_tmp_extra(void *tmp)
{
return PTR_ALIGN(tmp, __alignof__(struct esp_output_extra));
}
static inline u8 *esp_tmp_iv(struct crypto_aead *aead, void *tmp, int extralen)
{
return crypto_aead_ivsize(aead) ?
PTR_ALIGN((u8 *)tmp + extralen,
crypto_aead_alignmask(aead) + 1) : tmp + extralen;
}
static inline struct aead_request *esp_tmp_req(struct crypto_aead *aead, u8 *iv)
{
struct aead_request *req;
req = (void *)PTR_ALIGN(iv + crypto_aead_ivsize(aead),
crypto_tfm_ctx_alignment());
aead_request_set_tfm(req, aead);
return req;
}
static inline struct scatterlist *esp_req_sg(struct crypto_aead *aead,
struct aead_request *req)
{
return (void *)ALIGN((unsigned long)(req + 1) +
crypto_aead_reqsize(aead),
__alignof__(struct scatterlist));
}
static void esp_ssg_unref(struct xfrm_state *x, void *tmp)
{
struct crypto_aead *aead = x->data;
int extralen = 0;
u8 *iv;
struct aead_request *req;
struct scatterlist *sg;
if (x->props.flags & XFRM_STATE_ESN)
extralen += sizeof(struct esp_output_extra);
iv = esp_tmp_iv(aead, tmp, extralen);
req = esp_tmp_req(aead, iv);
/* Unref skb_frag_pages in the src scatterlist if necessary.
* Skip the first sg which comes from skb->data.
*/
if (req->src != req->dst)
for (sg = sg_next(req->src); sg; sg = sg_next(sg))
put_page(sg_page(sg));
}
#ifdef CONFIG_INET_ESPINTCP
struct esp_tcp_sk {
struct sock *sk;
struct rcu_head rcu;
};
static void esp_free_tcp_sk(struct rcu_head *head)
{
struct esp_tcp_sk *esk = container_of(head, struct esp_tcp_sk, rcu);
sock_put(esk->sk);
kfree(esk);
}
static struct sock *esp_find_tcp_sk(struct xfrm_state *x)
{
struct xfrm_encap_tmpl *encap = x->encap;
struct esp_tcp_sk *esk;
__be16 sport, dport;
struct sock *nsk;
struct sock *sk;
sk = rcu_dereference(x->encap_sk);
if (sk && sk->sk_state == TCP_ESTABLISHED)
return sk;
spin_lock_bh(&x->lock);
sport = encap->encap_sport;
dport = encap->encap_dport;
nsk = rcu_dereference_protected(x->encap_sk,
lockdep_is_held(&x->lock));
if (sk && sk == nsk) {
esk = kmalloc(sizeof(*esk), GFP_ATOMIC);
if (!esk) {
spin_unlock_bh(&x->lock);
return ERR_PTR(-ENOMEM);
}
RCU_INIT_POINTER(x->encap_sk, NULL);
esk->sk = sk;
call_rcu(&esk->rcu, esp_free_tcp_sk);
}
spin_unlock_bh(&x->lock);
sk = inet_lookup_established(xs_net(x), &tcp_hashinfo, x->id.daddr.a4,
dport, x->props.saddr.a4, sport, 0);
if (!sk)
return ERR_PTR(-ENOENT);
if (!tcp_is_ulp_esp(sk)) {
sock_put(sk);
return ERR_PTR(-EINVAL);
}
spin_lock_bh(&x->lock);
nsk = rcu_dereference_protected(x->encap_sk,
lockdep_is_held(&x->lock));
if (encap->encap_sport != sport ||
encap->encap_dport != dport) {
sock_put(sk);
sk = nsk ?: ERR_PTR(-EREMCHG);
} else if (sk == nsk) {
sock_put(sk);
} else {
rcu_assign_pointer(x->encap_sk, sk);
}
spin_unlock_bh(&x->lock);
return sk;
}
static int esp_output_tcp_finish(struct xfrm_state *x, struct sk_buff *skb)
{
struct sock *sk;
int err;
rcu_read_lock();
sk = esp_find_tcp_sk(x);
err = PTR_ERR_OR_ZERO(sk);
if (err)
goto out;
bh_lock_sock(sk);
if (sock_owned_by_user(sk))
err = espintcp_queue_out(sk, skb);
else
err = espintcp_push_skb(sk, skb);
bh_unlock_sock(sk);
out:
rcu_read_unlock();
return err;
}
static int esp_output_tcp_encap_cb(struct net *net, struct sock *sk,
struct sk_buff *skb)
{
struct dst_entry *dst = skb_dst(skb);
struct xfrm_state *x = dst->xfrm;
return esp_output_tcp_finish(x, skb);
}
static int esp_output_tail_tcp(struct xfrm_state *x, struct sk_buff *skb)
{
int err;
local_bh_disable();
err = xfrm_trans_queue_net(xs_net(x), skb, esp_output_tcp_encap_cb);
local_bh_enable();
/* EINPROGRESS just happens to do the right thing. It
* actually means that the skb has been consumed and
* isn't coming back.
*/
return err ?: -EINPROGRESS;
}
#else
static int esp_output_tail_tcp(struct xfrm_state *x, struct sk_buff *skb)
{
kfree_skb(skb);
return -EOPNOTSUPP;
}
#endif
static void esp_output_done(struct crypto_async_request *base, int err)
{
struct sk_buff *skb = base->data;
struct xfrm_offload *xo = xfrm_offload(skb);
void *tmp;
struct xfrm_state *x;
if (xo && (xo->flags & XFRM_DEV_RESUME)) {
struct sec_path *sp = skb_sec_path(skb);
x = sp->xvec[sp->len - 1];
} else {
x = skb_dst(skb)->xfrm;
}
tmp = ESP_SKB_CB(skb)->tmp;
esp_ssg_unref(x, tmp);
kfree(tmp);
if (xo && (xo->flags & XFRM_DEV_RESUME)) {
if (err) {
XFRM_INC_STATS(xs_net(x), LINUX_MIB_XFRMOUTSTATEPROTOERROR);
kfree_skb(skb);
return;
}
skb_push(skb, skb->data - skb_mac_header(skb));
secpath_reset(skb);
xfrm_dev_resume(skb);
} else {
if (!err &&
x->encap && x->encap->encap_type == TCP_ENCAP_ESPINTCP)
esp_output_tail_tcp(x, skb);
else
xfrm_output_resume(skb->sk, skb, err);
}
}
/* Move ESP header back into place. */
static void esp_restore_header(struct sk_buff *skb, unsigned int offset)
{
struct ip_esp_hdr *esph = (void *)(skb->data + offset);
void *tmp = ESP_SKB_CB(skb)->tmp;
__be32 *seqhi = esp_tmp_extra(tmp);
esph->seq_no = esph->spi;
esph->spi = *seqhi;
}
static void esp_output_restore_header(struct sk_buff *skb)
{
void *tmp = ESP_SKB_CB(skb)->tmp;
struct esp_output_extra *extra = esp_tmp_extra(tmp);
esp_restore_header(skb, skb_transport_offset(skb) + extra->esphoff -
sizeof(__be32));
}
static struct ip_esp_hdr *esp_output_set_extra(struct sk_buff *skb,
struct xfrm_state *x,
struct ip_esp_hdr *esph,
struct esp_output_extra *extra)
{
/* For ESN we move the header forward by 4 bytes to
* accommodate the high bits. We will move it back after
* encryption.
*/
if ((x->props.flags & XFRM_STATE_ESN)) {
__u32 seqhi;
struct xfrm_offload *xo = xfrm_offload(skb);
if (xo)
seqhi = xo->seq.hi;
else
seqhi = XFRM_SKB_CB(skb)->seq.output.hi;
extra->esphoff = (unsigned char *)esph -
skb_transport_header(skb);
esph = (struct ip_esp_hdr *)((unsigned char *)esph - 4);
extra->seqhi = esph->spi;
esph->seq_no = htonl(seqhi);
}
esph->spi = x->id.spi;
return esph;
}
static void esp_output_done_esn(struct crypto_async_request *base, int err)
{
struct sk_buff *skb = base->data;
esp_output_restore_header(skb);
esp_output_done(base, err);
}
static struct ip_esp_hdr *esp_output_udp_encap(struct sk_buff *skb,
int encap_type,
struct esp_info *esp,
__be16 sport,
__be16 dport)
{
struct udphdr *uh;
__be32 *udpdata32;
unsigned int len;
len = skb->len + esp->tailen - skb_transport_offset(skb);
if (len + sizeof(struct iphdr) > IP_MAX_MTU)
return ERR_PTR(-EMSGSIZE);
uh = (struct udphdr *)esp->esph;
uh->source = sport;
uh->dest = dport;
uh->len = htons(len);
uh->check = 0;
*skb_mac_header(skb) = IPPROTO_UDP;
if (encap_type == UDP_ENCAP_ESPINUDP_NON_IKE) {
udpdata32 = (__be32 *)(uh + 1);
udpdata32[0] = udpdata32[1] = 0;
return (struct ip_esp_hdr *)(udpdata32 + 2);
}
return (struct ip_esp_hdr *)(uh + 1);
}
#ifdef CONFIG_INET_ESPINTCP
static struct ip_esp_hdr *esp_output_tcp_encap(struct xfrm_state *x,
struct sk_buff *skb,
struct esp_info *esp)
{
__be16 *lenp = (void *)esp->esph;
struct ip_esp_hdr *esph;
unsigned int len;
struct sock *sk;
len = skb->len + esp->tailen - skb_transport_offset(skb);
if (len > IP_MAX_MTU)
return ERR_PTR(-EMSGSIZE);
rcu_read_lock();
sk = esp_find_tcp_sk(x);
rcu_read_unlock();
if (IS_ERR(sk))
return ERR_CAST(sk);
*lenp = htons(len);
esph = (struct ip_esp_hdr *)(lenp + 1);
return esph;
}
#else
static struct ip_esp_hdr *esp_output_tcp_encap(struct xfrm_state *x,
struct sk_buff *skb,
struct esp_info *esp)
{
return ERR_PTR(-EOPNOTSUPP);
}
#endif
static int esp_output_encap(struct xfrm_state *x, struct sk_buff *skb,
struct esp_info *esp)
{
struct xfrm_encap_tmpl *encap = x->encap;
struct ip_esp_hdr *esph;
__be16 sport, dport;
int encap_type;
spin_lock_bh(&x->lock);
sport = encap->encap_sport;
dport = encap->encap_dport;
encap_type = encap->encap_type;
spin_unlock_bh(&x->lock);
switch (encap_type) {
default:
case UDP_ENCAP_ESPINUDP:
case UDP_ENCAP_ESPINUDP_NON_IKE:
esph = esp_output_udp_encap(skb, encap_type, esp, sport, dport);
break;
case TCP_ENCAP_ESPINTCP:
esph = esp_output_tcp_encap(x, skb, esp);
break;
}
if (IS_ERR(esph))
return PTR_ERR(esph);
esp->esph = esph;
return 0;
}
int esp_output_head(struct xfrm_state *x, struct sk_buff *skb, struct esp_info *esp)
{
u8 *tail;
int nfrags;
int esph_offset;
struct page *page;
struct sk_buff *trailer;
int tailen = esp->tailen;
/* this is non-NULL only with TCP/UDP Encapsulation */
if (x->encap) {
int err = esp_output_encap(x, skb, esp);
if (err < 0)
return err;
}
if (ALIGN(tailen, L1_CACHE_BYTES) > PAGE_SIZE ||
ALIGN(skb->data_len, L1_CACHE_BYTES) > PAGE_SIZE)
goto cow;
if (!skb_cloned(skb)) {
if (tailen <= skb_tailroom(skb)) {
nfrags = 1;
trailer = skb;
tail = skb_tail_pointer(trailer);
goto skip_cow;
} else if ((skb_shinfo(skb)->nr_frags < MAX_SKB_FRAGS)
&& !skb_has_frag_list(skb)) {
int allocsize;
struct sock *sk = skb->sk;
struct page_frag *pfrag = &x->xfrag;
esp->inplace = false;
allocsize = ALIGN(tailen, L1_CACHE_BYTES);
spin_lock_bh(&x->lock);
if (unlikely(!skb_page_frag_refill(allocsize, pfrag, GFP_ATOMIC))) {
spin_unlock_bh(&x->lock);
goto cow;
}
page = pfrag->page;
get_page(page);
tail = page_address(page) + pfrag->offset;
esp_output_fill_trailer(tail, esp->tfclen, esp->plen, esp->proto);
nfrags = skb_shinfo(skb)->nr_frags;
__skb_fill_page_desc(skb, nfrags, page, pfrag->offset,
tailen);
skb_shinfo(skb)->nr_frags = ++nfrags;
pfrag->offset = pfrag->offset + allocsize;
spin_unlock_bh(&x->lock);
nfrags++;
skb->len += tailen;
skb->data_len += tailen;
skb->truesize += tailen;
if (sk && sk_fullsock(sk))
refcount_add(tailen, &sk->sk_wmem_alloc);
goto out;
}
}
cow:
esph_offset = (unsigned char *)esp->esph - skb_transport_header(skb);
nfrags = skb_cow_data(skb, tailen, &trailer);
if (nfrags < 0)
goto out;
tail = skb_tail_pointer(trailer);
esp->esph = (struct ip_esp_hdr *)(skb_transport_header(skb) + esph_offset);
skip_cow:
esp_output_fill_trailer(tail, esp->tfclen, esp->plen, esp->proto);
pskb_put(skb, trailer, tailen);
out:
return nfrags;
}
EXPORT_SYMBOL_GPL(esp_output_head);
int esp_output_tail(struct xfrm_state *x, struct sk_buff *skb, struct esp_info *esp)
{
u8 *iv;
int alen;
void *tmp;
int ivlen;
int assoclen;
int extralen;
struct page *page;
struct ip_esp_hdr *esph;
struct crypto_aead *aead;
struct aead_request *req;
struct scatterlist *sg, *dsg;
struct esp_output_extra *extra;
int err = -ENOMEM;
assoclen = sizeof(struct ip_esp_hdr);
extralen = 0;
if (x->props.flags & XFRM_STATE_ESN) {
extralen += sizeof(*extra);
assoclen += sizeof(__be32);
}
aead = x->data;
alen = crypto_aead_authsize(aead);
ivlen = crypto_aead_ivsize(aead);
tmp = esp_alloc_tmp(aead, esp->nfrags + 2, extralen);
if (!tmp)
goto error;
extra = esp_tmp_extra(tmp);
iv = esp_tmp_iv(aead, tmp, extralen);
req = esp_tmp_req(aead, iv);
sg = esp_req_sg(aead, req);
if (esp->inplace)
dsg = sg;
else
dsg = &sg[esp->nfrags];
esph = esp_output_set_extra(skb, x, esp->esph, extra);
esp->esph = esph;
sg_init_table(sg, esp->nfrags);
err = skb_to_sgvec(skb, sg,
(unsigned char *)esph - skb->data,
assoclen + ivlen + esp->clen + alen);
if (unlikely(err < 0))
goto error_free;
if (!esp->inplace) {
int allocsize;
struct page_frag *pfrag = &x->xfrag;
allocsize = ALIGN(skb->data_len, L1_CACHE_BYTES);
spin_lock_bh(&x->lock);
if (unlikely(!skb_page_frag_refill(allocsize, pfrag, GFP_ATOMIC))) {
spin_unlock_bh(&x->lock);
goto error_free;
}
skb_shinfo(skb)->nr_frags = 1;
page = pfrag->page;
get_page(page);
/* replace page frags in skb with new page */
__skb_fill_page_desc(skb, 0, page, pfrag->offset, skb->data_len);
pfrag->offset = pfrag->offset + allocsize;
spin_unlock_bh(&x->lock);
sg_init_table(dsg, skb_shinfo(skb)->nr_frags + 1);
err = skb_to_sgvec(skb, dsg,
(unsigned char *)esph - skb->data,
assoclen + ivlen + esp->clen + alen);
if (unlikely(err < 0))
goto error_free;
}
if ((x->props.flags & XFRM_STATE_ESN))
aead_request_set_callback(req, 0, esp_output_done_esn, skb);
else
aead_request_set_callback(req, 0, esp_output_done, skb);
aead_request_set_crypt(req, sg, dsg, ivlen + esp->clen, iv);
aead_request_set_ad(req, assoclen);
memset(iv, 0, ivlen);
memcpy(iv + ivlen - min(ivlen, 8), (u8 *)&esp->seqno + 8 - min(ivlen, 8),
min(ivlen, 8));
ESP_SKB_CB(skb)->tmp = tmp;
err = crypto_aead_encrypt(req);
switch (err) {
case -EINPROGRESS:
goto error;
case -ENOSPC:
err = NET_XMIT_DROP;
break;
case 0:
if ((x->props.flags & XFRM_STATE_ESN))
esp_output_restore_header(skb);
}
if (sg != dsg)
esp_ssg_unref(x, tmp);
if (!err && x->encap && x->encap->encap_type == TCP_ENCAP_ESPINTCP)
err = esp_output_tail_tcp(x, skb);
error_free:
kfree(tmp);
error:
return err;
}
EXPORT_SYMBOL_GPL(esp_output_tail);
static int esp_output(struct xfrm_state *x, struct sk_buff *skb)
{
int alen;
int blksize;
struct ip_esp_hdr *esph;
struct crypto_aead *aead;
struct esp_info esp;
esp.inplace = true;
esp.proto = *skb_mac_header(skb);
*skb_mac_header(skb) = IPPROTO_ESP;
/* skb is pure payload to encrypt */
aead = x->data;
alen = crypto_aead_authsize(aead);
esp.tfclen = 0;
if (x->tfcpad) {
struct xfrm_dst *dst = (struct xfrm_dst *)skb_dst(skb);
u32 padto;
padto = min(x->tfcpad, xfrm_state_mtu(x, dst->child_mtu_cached));
if (skb->len < padto)
esp.tfclen = padto - skb->len;
}
blksize = ALIGN(crypto_aead_blocksize(aead), 4);
esp.clen = ALIGN(skb->len + 2 + esp.tfclen, blksize);
esp.plen = esp.clen - skb->len - esp.tfclen;
esp.tailen = esp.tfclen + esp.plen + alen;
esp.esph = ip_esp_hdr(skb);
esp.nfrags = esp_output_head(x, skb, &esp);
if (esp.nfrags < 0)
return esp.nfrags;
esph = esp.esph;
esph->spi = x->id.spi;
esph->seq_no = htonl(XFRM_SKB_CB(skb)->seq.output.low);
esp.seqno = cpu_to_be64(XFRM_SKB_CB(skb)->seq.output.low +
((u64)XFRM_SKB_CB(skb)->seq.output.hi << 32));
skb_push(skb, -skb_network_offset(skb));
return esp_output_tail(x, skb, &esp);
}
static inline int esp_remove_trailer(struct sk_buff *skb)
{
struct xfrm_state *x = xfrm_input_state(skb);
struct crypto_aead *aead = x->data;
int alen, hlen, elen;
int padlen, trimlen;
__wsum csumdiff;
u8 nexthdr[2];
int ret;
alen = crypto_aead_authsize(aead);
hlen = sizeof(struct ip_esp_hdr) + crypto_aead_ivsize(aead);
elen = skb->len - hlen;
if (skb_copy_bits(skb, skb->len - alen - 2, nexthdr, 2))
BUG();
ret = -EINVAL;
padlen = nexthdr[0];
if (padlen + 2 + alen >= elen) {
net_dbg_ratelimited("ipsec esp packet is garbage padlen=%d, elen=%d\n",
padlen + 2, elen - alen);
goto out;
}
trimlen = alen + padlen + 2;
if (skb->ip_summed == CHECKSUM_COMPLETE) {
csumdiff = skb_checksum(skb, skb->len - trimlen, trimlen, 0);
skb->csum = csum_block_sub(skb->csum, csumdiff,
skb->len - trimlen);
}
pskb_trim(skb, skb->len - trimlen);
ret = nexthdr[1];
out:
return ret;
}
int esp_input_done2(struct sk_buff *skb, int err)
{
const struct iphdr *iph;
struct xfrm_state *x = xfrm_input_state(skb);
struct xfrm_offload *xo = xfrm_offload(skb);
struct crypto_aead *aead = x->data;
int hlen = sizeof(struct ip_esp_hdr) + crypto_aead_ivsize(aead);
int ihl;
if (!xo || !(xo->flags & CRYPTO_DONE))
kfree(ESP_SKB_CB(skb)->tmp);
if (unlikely(err))
goto out;
err = esp_remove_trailer(skb);
if (unlikely(err < 0))
goto out;
iph = ip_hdr(skb);
ihl = iph->ihl * 4;
if (x->encap) {
struct xfrm_encap_tmpl *encap = x->encap;
struct tcphdr *th = (void *)(skb_network_header(skb) + ihl);
struct udphdr *uh = (void *)(skb_network_header(skb) + ihl);
__be16 source;
switch (x->encap->encap_type) {
case TCP_ENCAP_ESPINTCP:
source = th->source;
break;
case UDP_ENCAP_ESPINUDP:
case UDP_ENCAP_ESPINUDP_NON_IKE:
source = uh->source;
break;
default:
WARN_ON_ONCE(1);
err = -EINVAL;
goto out;
}
/*
* 1) if the NAT-T peer's IP or port changed then
* advertize the change to the keying daemon.
* This is an inbound SA, so just compare
* SRC ports.
*/
if (iph->saddr != x->props.saddr.a4 ||
source != encap->encap_sport) {
xfrm_address_t ipaddr;
ipaddr.a4 = iph->saddr;
km_new_mapping(x, &ipaddr, source);
/* XXX: perhaps add an extra
* policy check here, to see
* if we should allow or
* reject a packet from a
* different source
* address/port.
*/
}
/*
* 2) ignore UDP/TCP checksums in case
* of NAT-T in Transport Mode, or
* perform other post-processing fixes
* as per draft-ietf-ipsec-udp-encaps-06,
* section 3.1.2
*/
if (x->props.mode == XFRM_MODE_TRANSPORT)
skb->ip_summed = CHECKSUM_UNNECESSARY;
}
skb_pull_rcsum(skb, hlen);
if (x->props.mode == XFRM_MODE_TUNNEL)
skb_reset_transport_header(skb);
else
skb_set_transport_header(skb, -ihl);
/* RFC4303: Drop dummy packets without any error */
if (err == IPPROTO_NONE)
err = -EINVAL;
out:
return err;
}
EXPORT_SYMBOL_GPL(esp_input_done2);
static void esp_input_done(struct crypto_async_request *base, int err)
{
struct sk_buff *skb = base->data;
xfrm_input_resume(skb, esp_input_done2(skb, err));
}
static void esp_input_restore_header(struct sk_buff *skb)
{
esp_restore_header(skb, 0);
__skb_pull(skb, 4);
}
static void esp_input_set_header(struct sk_buff *skb, __be32 *seqhi)
{
struct xfrm_state *x = xfrm_input_state(skb);
struct ip_esp_hdr *esph;
/* For ESN we move the header forward by 4 bytes to
* accommodate the high bits. We will move it back after
* decryption.
*/
if ((x->props.flags & XFRM_STATE_ESN)) {
esph = skb_push(skb, 4);
*seqhi = esph->spi;
esph->spi = esph->seq_no;
esph->seq_no = XFRM_SKB_CB(skb)->seq.input.hi;
}
}
static void esp_input_done_esn(struct crypto_async_request *base, int err)
{
struct sk_buff *skb = base->data;
esp_input_restore_header(skb);
esp_input_done(base, err);
}
/*
* Note: detecting truncated vs. non-truncated authentication data is very
* expensive, so we only support truncated data, which is the recommended
* and common case.
*/
static int esp_input(struct xfrm_state *x, struct sk_buff *skb)
{
struct crypto_aead *aead = x->data;
struct aead_request *req;
struct sk_buff *trailer;
int ivlen = crypto_aead_ivsize(aead);
int elen = skb->len - sizeof(struct ip_esp_hdr) - ivlen;
int nfrags;
int assoclen;
int seqhilen;
__be32 *seqhi;
void *tmp;
u8 *iv;
struct scatterlist *sg;
int err = -EINVAL;
if (!pskb_may_pull(skb, sizeof(struct ip_esp_hdr) + ivlen))
goto out;
if (elen <= 0)
goto out;
assoclen = sizeof(struct ip_esp_hdr);
seqhilen = 0;
if (x->props.flags & XFRM_STATE_ESN) {
seqhilen += sizeof(__be32);
assoclen += seqhilen;
}
if (!skb_cloned(skb)) {
if (!skb_is_nonlinear(skb)) {
nfrags = 1;
goto skip_cow;
} else if (!skb_has_frag_list(skb)) {
nfrags = skb_shinfo(skb)->nr_frags;
nfrags++;
goto skip_cow;
}
}
err = skb_cow_data(skb, 0, &trailer);
if (err < 0)
goto out;
nfrags = err;
skip_cow:
err = -ENOMEM;
tmp = esp_alloc_tmp(aead, nfrags, seqhilen);
if (!tmp)
goto out;
ESP_SKB_CB(skb)->tmp = tmp;
seqhi = esp_tmp_extra(tmp);
iv = esp_tmp_iv(aead, tmp, seqhilen);
req = esp_tmp_req(aead, iv);
sg = esp_req_sg(aead, req);
esp_input_set_header(skb, seqhi);
sg_init_table(sg, nfrags);
err = skb_to_sgvec(skb, sg, 0, skb->len);
if (unlikely(err < 0)) {
kfree(tmp);
goto out;
}
skb->ip_summed = CHECKSUM_NONE;
if ((x->props.flags & XFRM_STATE_ESN))
aead_request_set_callback(req, 0, esp_input_done_esn, skb);
else
aead_request_set_callback(req, 0, esp_input_done, skb);
aead_request_set_crypt(req, sg, sg, elen + ivlen, iv);
aead_request_set_ad(req, assoclen);
err = crypto_aead_decrypt(req);
if (err == -EINPROGRESS)
goto out;
if ((x->props.flags & XFRM_STATE_ESN))
esp_input_restore_header(skb);
err = esp_input_done2(skb, err);
out:
return err;
}
static int esp4_err(struct sk_buff *skb, u32 info)
{
struct net *net = dev_net(skb->dev);
const struct iphdr *iph = (const struct iphdr *)skb->data;
struct ip_esp_hdr *esph = (struct ip_esp_hdr *)(skb->data+(iph->ihl<<2));
struct xfrm_state *x;
switch (icmp_hdr(skb)->type) {
case ICMP_DEST_UNREACH:
if (icmp_hdr(skb)->code != ICMP_FRAG_NEEDED)
return 0;
break;
case ICMP_REDIRECT:
break;
default:
return 0;
}
x = xfrm_state_lookup(net, skb->mark, (const xfrm_address_t *)&iph->daddr,
esph->spi, IPPROTO_ESP, AF_INET);
if (!x)
return 0;
if (icmp_hdr(skb)->type == ICMP_DEST_UNREACH)
ipv4_update_pmtu(skb, net, info, 0, IPPROTO_ESP);
else
ipv4_redirect(skb, net, 0, IPPROTO_ESP);
xfrm_state_put(x);
return 0;
}